ANALYSIS AND MANAGEMENT OF CERVICOGENIC HEADACHES: PART I OF II

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Analysis and Management of Cervicogenic Headaches: Part I of II

IN 1983, TODAY'S CHIROPRACTIC published my article on headaches that reflected the chiropractic thoughts on the causes of headaches at that time. In particular, it discussed the subluxation basis of cervicogenic headaches.

There is little new in chiropractic on this subject; but, it is timely to reevaluate how we can better serve our patients through greater interprofessional cooperation and open the doors for referrals from M.D.s in the care of the headache sufferer.

Recent studies and articles have been touting a so-called breakthrough in medical science -- indisputable evidence that neck problems are the major cause of most headaches. I will reveal some good news, some bad news and a little bit of the ugly truth regarding cervicogenic headaches. Headaches are one of the most frequent presenting complaints to both the general practitioner and neurologic specialist, representing up to 25 million visits per year.

The good news is seeing chiropractic's effectiveness being proven by independent scientific studies, medical or otherwise. Every time there is additional proof to support the value of chiropractic, we should seize the opportunity to inform and educate our communities.

This particular information needs to be shared with the medical community in your town. Remember that if you don't do it, it won't get done!

The bad news is that medical practitioners are taking the new information and, of course, applying medical solutions without turning to chiropractic. Current medical treatment for cervicogenic headaches include a few conservative methods like physical therapy, exercise and oral medication.

But, for the most part, they are using more invasive procedures such as trigger point injections, facet injections, nerve blocks, epidural steroid injections, nerve rhizotomy and rhizolysis, discotomy, discectomy and cervical fusion.

Granted, there may be cause to resort to these procedures at times, however, it is not acceptable that chiropractic is rarely included in the case management of cervicogenic headache patients by medical practitioners. As they say, "When things don't change,...things don't change."

The ugly truth is that nothing has changed very much. How many referrals have you received from an M.D. lately? M.D.s are not referring headache patients for chiropractic care, even when their headaches are clearly neck-related. They are doing business as usual and simply using different ways to use drugs in relieving headaches. The game is still the same. The only difference is that the evidence is leaning more toward chiropractic than ever before, and have to be prepared to reach out with this new information.

I want to focus on providing you, the practicing D.C., with information about what is being done medically, as well as information on helping you with tools for better case management of the headache patients who are coming into your office.

ANATOMICAL CONSIDERATIONS

There is overwhelming agreement that craniovertebral dysfunction can, and very often does, cause a cervical origin headache or benign headache.

In an overview of the neuroanatomy of this region, we find that there is significant influence of the cervical spine dysfunction into the nature of head and facial pain. If we were to assume that at least half of the people who have cervical spine dysfunction or derangement in the craniovertebral region also have complaints of headache, we would also have to assume that treatment of these regions should reduce the afferent/sensory input to the trigeminal cervical nucleus and reduce or eliminate the headache.

The cervical spine and associated muscular support of the head, interwoven with vessels and nerve supply in the head and upper extremities, compose a complex structure with many sites for the generation of pain. A reduction in the space in which nerves pass through or lie can result in pain and loss of function. If the pressure is acute, pain is more likely to occur. Loss of function is generally the result of more prolonged and continuous pressure.

The first three nerves of the neck supply the joints of the upper cervical spine, the ligaments and muscles. These sensory nerves carry the sensation of pain from the head.

At the C2 level, there is also communication with the sensory nucleus of the trigeminal nerve, which supplies sensation to the face. The major sensory divisions of the trigeminal nerve carry primarily light touch, pain, and temperature pathways to the thalamus by way of the tract of trigeminal cervical nucleus. Again, there is a significant relationship between sensation and dysfunction in the face and head region, and their relationship to craniovertebral region dysfunction; hence, there is referred pain in either direction.

Sensory information is transmitted to the dorsal rami, and exits the spinal cord opposite each cervical articulation. At each cervical level, two branches will penetrate the joint capsule and deliver sensory input back to the trigeminal cervical nucleus through these innervations. Not only do these branches supply the joint capsule and surrounding soft tissues, but also the musculature in the region.

Along with supplying the articular capsule of the joints and some deep muscles in the cervical spine, communications are also seen with the spinal ganglion, dorsal and ventral rami, as well as the sympathetic trunk. The sensation to the posterior aspect of the scalp is supplied by the C2 and C3 nerves, and pain may be referred directly along these nerves.

The sensation to the anterior scalp and face is supplied by the three divisions of the trigeminal nerve, with considerable overlap between these branches and the branches of the upper cervical nerves. With any dysfunction of the upper cervical spine, including the joints, muscles or ligaments, there may be local neck pain, but often referred pain into the head or face, manifesting itself as a headache.

The greater and lesser occipital nerves are sensory nerves which enter into the second, and to some extent the third, cervical segments. The nerves enter the spinal cord via the tract of Lissauer to terminate in the substantia gelatenosa of the upper cervical cord, where they synapse. The infratentorial intracranial structures are innervated by the upper three cervical nerves. Sensory cutaneous distribution in the occipital nerve is over the back of the head anteriorly to the borders of the innervation of the first division of the trigeminal nerve. The C2 component is a more medial band extending from the superior nuchal line to this boundary. C1, when present, innervates an overlapping area more posteriorly.

The greater occipital nerve passes over the superior nuchal line midway between the mastoid process on the occipital protuberance just lateral to the insertion of the nuchal ligaments. The lesser occipital protuberance is just lateral to the insertion of the nuchal ligaments. The lesser occipital nerve passes laterally to the greater occipital nerve over the nuchal ridge. The greater occipital nerve runs transversely and then turns at right angles to run posteriorly. It then emerges through the aperture above the aponeurotic sling between the trapezius and the sternomastoid.

The sites of nerve compression in the neck are the intervertebral foramina, the spinal canal, the interscalene space and the course of the occipital nerves through the trapezius muscle at the base of the skull. Impairment or free movement at the joints, discs or ligaments may lead to irritation of sensitive structures of the joints and soft tissue of the neck.

NEUROPHYSIOLOGICAL CONSIDERATIONS -- REFERRED PAIN AND FACILITATION

Referred pain is a recognized, but difficult, phenomenon to understand completely. Many times, the areas where pain is subjectively felt are not necessarily the areas that are involved with the pain origination.

Referred pain is primarily a central nervous system phenomenon. A description and simple explanation for this is that of "phantom pain" of an amputated limb. In this example, the limb need not even be present, and the patient can present with severe and disabling pain referred to the lost limb. Therefore, pain is "recognized" within the central nervous system, although it is "perceived" by the patient to be in the tissue, such in these phantom limb pains.

Following this central phenomenon model, the ability of the cervical nucleus, combined with the trigeminal nucleus in transmitting noxious stimulus in either direction, explains many of the phenomena occurring in head and neck pain and in our discussion of cervicogenic headaches.

Referred pain from either the craniovertebral region or the TMJ/head region can refer pain to either area. Thus, the craniovertebral region can give the sensation of pain in not only the suboccipital and occipital region, but also in the temporal and frontal area of the head and the retro-orbital region. Conversely, TMJ dysfunction can refer pain in and around the ear, the craniovertebral region and may develop scalp soreness and general or burning neck pain.

Pain receptors are nociceptors generally described as unspecialized free nerve endings. They are highly branched and have large receptor fields. The overall sensitivity of tissue to noxious stimulation is generally influenced by the density of the nociceptors. Many times, with repeated stimulation of nociceptors, other sensations may start to develop and there is a convergence of nociceptive afferents in the dorsal horn of the spinal cord.

When discussing referred pain, visceral referred pain is always in the direction from visceral to somatic structures. When discussing the areas innervated by the trigeminal or cervical nerves, referred pain can occur in either direction.

Essentially, noxious cervical spine pain and inflammation may give rise to pain in the trigeminal area of innervation and, likewise, noxious trigeminal input may be perceived as pain in the cervical spine.

FACILITATION

Facilitation can be described as a function of the nervous system, whereby repeated stimuli lower the firing threshold of neurons, requiring less and less stimulation to produce a greater and greater response. When this occurs along nociceptors, there is a greater preponderance for pain.

Upper cervical segmental dysfunction creates the opportunity for repetitive stimulation, which also increases as the cervical instability degresses. Spinal adjustments help to stabilize the upper cervical spine and minimize the repeated noxious stimuli that produce cervicogenic headaches.

HOW NAIVE CAN ONE GET?

At first, upon hearing of the increased acceptance of the cervicogenic headache classification by the medical profession, I thought that a new day had dawned for interprofessional relationships to flourish in the management of headache patients.

Unfortunately, the more I researched the treatment applications by the medical profession, it became apparent that old ways are hard to change. One would think that, with strong evidence of the safety and effectiveness of chiropractic management of headaches, M.D.s would be referring the cervicogenic headache cases for chiropractic care.

Common sense would dictate a prudent protocol that includes a reasonable trial of chiropractic adjustments as a first line in the management of most headaches. Those cases that did not respond would next undergo conservative medical procedures, and, lastly, would be considered for the available invasive methods.

The sad truth is, the lack of personal or professional exposure to chiropractic continues to keep the M.D.s clueless and suspicious of our profession. Without adequate communication, that reality remains unchanged and chiropractic continues to be excluded from medical referral patterns.

In the final part of the article, to appear in the January/February 1998 issue, we will look at how medical "pain clinics" care for their cervicogenic headache patients, without knowing or opting to consider chiropractic, and a proposed model for case management.

Article copyright Life University.

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By Michel Tetrault

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